Allow pages on the OSX app launcher to be turned while dragging.

ui/app_list/cocoa/apps_grid_controller.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_APP_LIST_COCOA_APPS_GRID_CONTROLLER_H_
 #define UI_APP_LIST_COCOA_APPS_GRID_CONTROLLER_H_
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/memory/scoped_nsobject.h"
@@ skipping 17 matching lines @@
 @interface AppsGridController : NSViewController<GestureScrollDelegate,
                                                  AppListPagerDelegate> {
  @private
   scoped_ptr<app_list::AppListModel> model_;
   app_list::AppListViewDelegate* delegate_;  // Weak. Owned by view controller.
   scoped_ptr<app_list::AppsGridDelegateBridge> bridge_;
 
   scoped_nsobject<AppsCollectionViewDragManager> dragManager_;
   scoped_nsobject<NSMutableArray> pages_;
   scoped_nsobject<NSMutableArray> items_;
+  scoped_nsobject<NSTimer> scrollWhileDraggingTimer_;
 
   id<AppsPaginationModelObserver> paginationObserver_;
 
   // Index of the currently visible page.
   size_t visiblePage_;
+  // The page to which the view is currently animating a scroll.
+  size_t targetScrollPage_;
+  // The page to start scrolling to when the timer expires.
+  size_t scheduledScrollPage_;
 
   // Whether we are currently animating a scroll to the nearest page.
   BOOL animatingScroll_;
 }
 
 @property(assign, nonatomic) id<AppsPaginationModelObserver> paginationObserver;
 
 + (void)setScrollAnimationDuration:(NSTimeInterval)duration;
 
 - (NSCollectionView*)collectionViewAtPageIndex:(size_t)pageIndex;
@@ skipping 15 matching lines @@
 
 // Return the number of pages of icons in the grid.
 - (size_t)pageCount;
 
 // Return the number of items over all pages in the grid.
 - (size_t)itemCount;
 
 // Scroll to a page in the grid view with an animation.
 - (void)scrollToPage:(size_t)pageIndex;
 
+// Start a timer to scroll to a new page, if |locationInWindow| is to the left
+// or the right of the view, or if it is over a pager segment. Cancels any
+// existing timer if the target page changes.
+- (void)maybeChangePageForPoint:(NSPoint)locationInWindow;
+
+// Cancel a timer that may have been set by maybeChangePageForPoint().
+- (void)cancelScrollTimer;
+
 // Moves an item within the view only, for dragging or in response to model
 // changes.
 - (void)moveItemInView:(size_t)fromIndex
            toItemIndex:(size_t)toIndex;
 
 // Moves an item in the item model. Does not adjust the view.
 - (void)moveItemWithIndex:(size_t)itemIndex
              toModelIndex:(size_t)modelIndex;
 
 // Return the index of the selected item.
 - (NSUInteger)selectedItemIndex;
 
 // Moves the selection to the given index.
 - (void)selectItemAtIndex:(NSUInteger)index;
 
 // Handle key actions. Similar to doCommandBySelector from NSResponder but that
 // requires this class to be in the responder chain. Instead this method is
 // invoked by the AppListViewController.
 // Returns YES if this handled navigation or launched an app.
 - (BOOL)handleCommandBySelector:(SEL)command;
 
 @end
 
 @interface AppsGridController(TestingAPI)
 
 - (AppsCollectionViewDragManager*)dragManager;
+- (size_t)scheduledScrollPage;
 
 @end
 
 #endif  // UI_APP_LIST_COCOA_APPS_GRID_CONTROLLER_H_